But, after 16 flights had to be delayed, they gave police the go ahead to shoot the 10-month-old border collie and German shorthaired pointer mix. They insisted it was a last resort.

The shooting was condemned by animal rights activists and others.

The dog, named Grizz, was training to be an Aviation Security explosion detector and was six months away from graduation, CNN reported.

After handlers tried unsuccessfully to recapture him, and to coax him off the runway, airport staff told police to shoot him.

Then they got on Twitter and reported he had been recaptured.

Not until an hour later did they reveal the dog had been killed.

According to the New Zealand Herald, Grizz was not on the tarmac but on the outer perimeter of the airfield when he was shot.

SAFE for Animals Ambassador Hans Kriek condemned the killing, asking why the animal wasn’t tranquilized, but a spokesman for the Civil Aviation Authority (CAA) said he “didn’t believe” that had been an option.

Grizz escaped from his handler at around 4.30 a.m. Friday (local time) and ran out onto the tarmac at Auckland Airport, according to the CAA spokesman.

“He was on an initial airport environment socialization program as part of his training … The airport Emergency Operations Center was activated and a full search was commenced,” he said in a statement.

But the spokesman said it was too dark and the area too large to quickly find and contain the puppy.

“We tried everything, food, toys, other dogs, but nothing would work … In these difficult circumstances the Airport’s Emergency Operations Center team decided to have the dog destroyed,” he said

Animal activist Kriek said other alternatives should have been explored.

“Ultimately they have to call the police in to shoot the dog, and the police have access to tranquilizer guns, and there’s also a zoo nearby that would have one as well. So we don’t understand why they didn’t do that,” he said.

An airport spokesman said the question of a tranquilizer gun, and the entire incident, would be reviewed.